xviii ILLUSTRATIONS 



PAGE 



Fig. 26. Illustrating the relationship between bacterial activities 



in a soil and crop yield 116 



Fig. 27. Nitrifying bacteria 121 



Fig. 28. Nitrifying bacteria 121 



Fig. 29. Nitrogen produced by various processes 139 



Fig. 30. Clostridium fasteurianum 141 



Fig. 31. Azotobacter cells 148 



Fig. 32. Pigments produced by Azotobacter facing page 14.8 



Fig. 33. Nodules on soy beans 159 



Fig. 34.. Influence of legumes on crop yield 164 



Fig. 35. Effect of inoculation on alfalfa 166 



Fig. 36. Colonies of cellulose ferments 186 



Fig. 37. Cellulose ferments 187 



Fig. 38. Alkali soils 190 



Fig. 39. Vegetation on alkali and alkali-free soil 191 



Fig. 40. Influence of alkali on growth of crimson clover 198 



Fig. 41. Arsenic obtained from various soils 206 



Fig. 42. Beans grown on arsenic-treated soil 208 



Fig. 43. Beets grown on manured and unmanured soil 214 



Fig. 44. Relationship between nitrification and crop yield 217 



Fig. 45. Soil injured by alkaline water 226 



